The xpilot replay programs do not have built-in support for xz compression.Therefor you will have to decompress the file explicitly before playback.On the fly (without creating a new file or modifying the xz compressed xpr) you can use: xzcat recording.xpr.xz | bloodspilot-replay -

P.S.: Had to add a `.xp' suffix to the attachment to have it accepted by the board ...